The art is continually seeking new hydrochlorofluorocarbons to be used in many applications. Hydrochlorofluorocarbons are considered to be stratospherically safe substitutes for presently used fully halogenated chlorofluorocarbons. The latter are suspected of causing environmental problems in connection with the earth's protective ozone layer. Mathematical models have substantiated that hydrochlorofluorocarbons, such as dichlorotrifluoroethane, will not adversely affect atmospheric chemistry, being negligible contributors to ozone depletion and to green-house global warming in comparison to the fully halogenated species.
Dichlorotrifluoroethane is being considered for use in many applications including as a solvent and a refrigerant. Dichlorotrifluoroethane hydrolyzes to form hydrogen chloride. While dichlorotrifluoroethane is useful in many applications, dichlorotrifluoroethane should be stabilized against possible changes during storage and use. When metallic materials are present, the problem is worsened because the metal acts as a catalyst and causes the hydrolysis of dichlorotrifluoroethane to increase exponentially. Also, ultraviolet light decomposes dichlorotrifluoroethane.
In addition to dichlorotrifluoroethane reacting with water to form acids such as hydrogen chloride and hydrogen fluoride, dichlorotrifluoroethane also reacts with alcoholic hydroxyl groups to form aldehydes and ketones. Known stabilizers for compositions of 1,1-dichloro-2,2,2-trifluoroethane and alcohol include: epoxy compounds as taught by Kokai Patent Publication 56,630 published Mar. 3, 1989; combinations of styrene and epoxy compounds as taught by Kokai Patent Publication 56,631 published Mar. 3, 1989; combinations of styrene compounds and phenols as taught by Kokai Patent Publication 56,632 published Mar. 3, 1989; combinations of epoxy and styrene compounds and phenols as taught by Kokai Patent Publication 128,944 published May 22, 1989; hydrocarbons containing nitro groups as taught by Kokai Patent Publication 128,944 published May 22, 1989; combinations of hydrocarbons containing nitro groups and epoxy compounds as taught by Kokai Patent Publication 128,945 published May 22, 1989; and phenols as taught by Kokai Patent Publication 265,042 published Oct. 23, 1989. Kokai Patent Publication 139,539 teaches 1,2-dichloro-1,1,2-trifluoroethane based azeotropic compositions which are stabilized with at least one of nitro compounds, phenols, amines, ethers, amylenes, esters, organic phosphites, epoxides, furans, alcohols, ketones, and triazoles.
Because dichlorotrifluoroethane may be used alone in many applications, it would be advantageous to have a stabilized dichlorotrifluoroethane. This ideally stabilized dichlorotrifluoroethane could then be used in many applications wherein dichlorotrifluoroethane is typically exposed to water, metallic materials, and ultraviolet light.
Dichlorotrifluoroethane has three isomers including 1,1-dichloro-2,2,2-trifluoroethane (known in the art as HCFC-123) and 1,2-dichloro-1,1,2-trifluoroethane (known in the art as HCFC-123a). R123 may replace trichlorofluoromethane (known in the art as R11) in many applications because environmental concerns over the use of R11 exist. R11 is currently used as a refrigerant in closed loop refrigeration systems; many of these systems are air-conditioning systems. R123 has properties similar to those of R11 so that it is possible to substitute R123 for R11 in refrigeration applications with minimal changes in equipment being required.
A problem arises in such a substitution. Refrigeration systems which use R11 generally use mineral oils to lubricate the compressor. We have found that the use of R123 and mineral oil results in the formation of 1-chloro-2,2,2-trifluoroethane (known in the art as HCFC-133a); in the absence of mineral oil, the use of R123 does not result in the formation of HCFC-133a. E. Long et al., Toxicol. Appl. Pharmacl. 72, 15 (1984) report that HCFC-133a is an animal carcinogen. Understandably, the potential presence of a known animal carcinogen is unacceptable in any commercial system.
As such, the need exists in the art for an additive which substantially minimizes the reaction of R123 with mineral oil.
Kokai Patent Publication 128,943 published May 22, 1989 teaches a method for stabilizing a hydrogen-containing furon such as R123 against alcoholic hydroxyl groups. The reference teaches that a three-component stabilizer system of a styrenic compound, a phenol, and an epoxy can be used for the storage stability of polyol which contains the hydrogen-containing furon as the foaming agent. The reference lists chlorotrifluoroethane as a useful hydrogen-containing furon.
Kokai Patent Publication 128,944 published May 22, 1989 teaches a method for stabilizing a hydrogen-containing furon such as R123 against alcoholic hydroxyl groups. The reference teaches that a stabilizer of a nitro-containing hydrocarbon such as nitromethane, 1-nitropropane, 2-nitropropane, or nitrobenzene can be used for the storage stability of polyol which contains the hydrogen-containing furon as the foaming agent. The reference lists chlorotrifluoroethane as a useful hydrogen-containing furon.
Kokai Patent Publication 128,945 published May 22, 1989 teaches a method for stabilizing a hydrogen-containing furon such as 1,1-dichloro-2,2,2-trifluoroethane against alcoholic hydroxyl groups. The reference teaches that a two-component stabilizer system of a nitro-containing hydrocarbon and an epoxy compound can be used for the storage stability of polyol which contains the hydrogen-containing furon as the foaming agent. The reference lists chlorotrifluoroethane as a useful hydrogen-containing furon.
In an attempt to solve this problem, we considered epoxides as taught by Kokai Patent Publication 179,699 published Oct. 12, 1984; and Kokai Patent Publication 281,199 published Dec. 11, 1988. As shown in Comparatives D through F below, we added epoxides to compositions of R123 and mineral oil and found that epoxides alone were ineffective in substantially reducing the reaction of R123 with mineral oil.
Also in an attempt to solve this problem, we considered phenols as listed in commonly assigned U.S. Pat. No. 4,755,316; Kokai Patent Publication 281,199 published Dec. 11, 1988; U.S. Pat. Nos. 4,812,246 and 4,851,144; commonly assigned U.S. Pat. No. 4,900,463; Kokai Patent Publication 102,296 published Apr. 13, 1990; U.S. Pat. No. 4,959,169; and commonly assigned U.S. Pat. No. 4,975,212. As shown in Comparatives B and C below, we added phenols to compositions of R123 and mineral oil and found that the phenols alone were ineffective in substantially reducing the reaction R123 with mineral oil.
We were then surprised to find that the combination of aromatic epoxide and phenol is effective in substantially reducing the reaction of R123 with mineral oil.
U.S. Pat. Nos. 4,248,726; 4,267,064; and 4,431,557 teach the addition of epoxides to compositions of refrigerants and lubricants. The references also teach that known additives such as phenol or amine type antioxidants; sulphur or phosphorus type oiliness improvers; silicone type antifoam agents; metal deactivators such as benzotriazole, amines, and acid esters; and load carrying additives such as phosphoric acid esters, phosphorous acid esters, thiophosphoric acid esters, organic sulfur compounds, and organic halogen compounds can be used. These references do not teach or suggest the present invention.
U.S. Pat. No. 4,948,525 teaches that known refrigerator oil additives such as phenol-type antioxidants such as di-tert-butyl-p-cresol; amine-type antioxidants such as phenyl-.alpha.-naphthylamine and N,N'-di(2-naphthyl)-p-phenylenediamine; load resistant additives such as zinc dithiophosphate, chlorinated paraffin, fatty acids, and sulfur type load resistant compounds; silicone-type antifoaming agents; metal inactivators such as benzotriazole; and hydrogen chloride captors such as glycidyl methacrylate and phosphite esters may be used in refrigeration compositions. The reference states that these additives may be used singly or jointly but does not teach or suggest the present invention.